Simultaneous catalytic removal of N2O and CH4 as the strong greenhouse-effect gases was found to be possible over an Fe-ion-exchanged BEA zeolite (Fe-BEA) by the selective catalytic reduction (SCR) of N2O with CH4. The direct decomposition of N2O (2N(2)O --> 2N(2) + O-2) and the oxidation of CH4 (CH4 + 2O(2) --> CO2 + 2H(2)O) over Fe-BEA zeolite required high temperature above 400 and 450 degrees C, respectively. Nevertheless, the catalytic reduction of N2O by adding CH4 over Fe-BEA zeolite readily occurred at much lower temperatures (ca. 250-350 degrees C) whether in the presence of O-2 or not. No oxidation of CH4 by O-2 took place at these temperatures. On the basis of these results and the kinetic studies, it was concluded that CH4 reacted selectively with N2O to produce N-2, CO2 and H2O over Fe-BEA zeolite even in the presence of excess O-2. Overall stoichiometry of the SCR of N2O with CH4 was determined as follows: 4N(2)O + CH4 --> 4N(2) + CO2 + 2H(2)O.